JP2001159318A - Cold power generator - Google Patents

Abstract

(57) [Summary] A cryogenic power generation device that generates power with high efficiency by utilizing the cryogenic heat of LNG, is safe, has a simple configuration, and does not require measures against NOx. A storage tank (7) for storing liquid carbon dioxide gas, a pump (8) for pumping the liquid carbon dioxide gas in the storage tank, and a carbon dioxide gas for re-vaporizing the liquid carbon dioxide gas pressurized by the pump using turbine exhaust gas and separating carbon dioxide gas from the turbine exhaust gas. A gas separator 4, a combustor 1 for burning clean fuel in the presence of high-pressure carbon dioxide gas re-evaporated by the carbon dioxide separator and oxygen b, and a gas turbine 2 for driving a generator using the combustion gas of the combustor as a power source , Carbon dioxide gas separated by carbon dioxide separator
The gas turbine is composed of a vaporizer 6 for liquefying and gasifying LNG by using a gas turbine, and an expansion turbine 11 provided in parallel with the gas turbine and introducing the remaining turbine exhaust gas separated from carbon dioxide gas.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquefied natural gas (L)
The present invention relates to a cryogenic power generator that effectively utilizes the cryogenic heat of NG) to generate power with high efficiency.

[0002]

2. Description of the Related Art When LNG is re-vaporized, most of the enormous energy required for liquefaction of LNG is discarded in the sea because it has been conventionally gasified using seawater and is not effectively used. Is the actual situation.

[0003] As a method of utilizing the cold energy possessed by LNG, for example, there are methods such as cryogenic power generation, air liquefaction separation, freezing warehouse, air conditioning, and substitution of a refrigerator. Among them, cryogenic power generation is the most effective. It seems to be a cold heat recovery method.

As conventional cold power generation, a Rankine cycle system as shown in FIG. 6, a natural gas direct expansion system as shown in FIG. 7, or a multiple medium application system as shown in FIG.

However, the Freon Rankine cycle system shown in FIG. 6, which uses Freon gas as the working medium, cannot be used in the future. In addition, the natural gas direct expansion system of FIG.
Although the system is simple, it is difficult to increase the output because the power generation output is small. Also, efficiency is low.

[0006] In addition, the multi-media application method as shown in FIG.
Gas turbine cycle A
And the CFC gas cycle B and the steam cycle C, the power generation system itself is very complicated. Also, the CFC cycle is
An alternative is needed for hydrocarbon-based refrigerants. Furthermore, since air (air) is taken into the RTR (combustor), NOx
Measures are needed.

In the figure, AIR is combustion air, AIR
-C is an air compressor, RTR is a combustor, GAS-
T is a gas turbine, ST-T is a steam turbine, FR-V
AP is Freon evaporator, FR-T is Freon turbine, FR
E-HX is CFC heat exchanger, LNG-CON is LNG heat exchanger, PRE-HX is preheater, LNG-VAP is LN
G evaporator, LNG-SH indicates an LNG superheater, NG-HT indicates a high-pressure natural gas turbine, and NG-LT indicates a low-pressure natural gas turbine.

[0008]

SUMMARY OF THE INVENTION The present invention has been made in order to overcome the above-mentioned conventional problems, and has as its object to efficiently utilize the cold stored in LNG to achieve high efficiency. Another object of the present invention is to provide a cryogenic power generation device that generates power in the above manner, is safe, has a simple device configuration, and does not require any measures against NOx.

[0009]

In order to solve the above-mentioned problems, a cryogenic power generator according to the present invention comprises a storage tank for storing liquid carbon dioxide gas, a pump for pumping liquid carbon dioxide gas from the storage tank, and increasing the pressure. The liquid carbon dioxide gas discharged from the pump is re-vaporized using the gas turbine exhaust gas, and a carbon dioxide gas separator for separating the carbon dioxide gas in the gas turbine exhaust gas, and the carbon dioxide gas re-vaporized by the carbon dioxide gas separator, and A combustor that burns clean fuel in the presence of oxygen, a gas turbine that drives a generator using the combustion gas generated by the combustor as a power source, and liquefies the carbon dioxide gas separated by the carbon dioxide separator. A carburetor that liquefies natural gas and gasifies liquefied natural gas, and is provided in parallel with the gas turbine and separates carbon dioxide by the carbon dioxide separator It is formed from the rest of the expansion turbine for introducing the gas turbine exhaust gas is.

According to the present invention, the pressure of the liquid carbon dioxide stored in the storage tank is increased by a pump and introduced into the carbon dioxide separator, where the gas is re-vaporized by utilizing the heat energy of the gas turbine exhaust gas. The re-vaporized carbon dioxide gas is supplied to the combustor.
The combustor is supplied with city gas and oxygen, which are clean fuels, in addition to carbon dioxide as a working fluid.

The combustion gas generated by the combustor is supplied to a gas turbine as a power source for driving a generator. Gas turbine exhaust gas discharged from the gas turbine is introduced into a carbon dioxide gas separator, where carbon dioxide in the exhaust gas is separated.
The separated carbon dioxide gas is introduced into a vaporizer to gasify the liquefied natural gas, while liquefying itself to become liquid carbon dioxide gas again. Since the remaining gas turbine exhaust gas from which the carbon dioxide gas has been separated has a pressure, it can be introduced into an expansion turbine attached to the gas turbine to contribute to power generation, and high efficiency can be achieved.

Further, immediately before introducing the remaining gas turbine exhaust gas from which the carbon dioxide gas has been separated by the carbon dioxide gas separator into the expansion turbine, it is reheated by a heater arranged upstream of the carbon dioxide gas separator to further generate electricity. Efficiency is improved.

Further, by introducing and cooling a part of the carbon dioxide gas supplied to the combustor to the turbine blades of the gas turbine,
High temperature and high pressure of the gas turbine can be measured.

On the other hand, another cryogenic power generation device according to the present invention comprises:
A storage tank for storing the liquid carbon dioxide gas, a pump for pumping the liquid carbon dioxide gas from the storage tank to increase the pressure, and re-vaporizing the liquid carbon dioxide gas discharged from the pump using the gas turbine exhaust gas, A carbon dioxide gas evaporator for separating gas, a combustor for burning clean fuel in the presence of carbon dioxide gas re-evaporated by the carbon dioxide gas evaporator and oxygen, and a combustion source generated by the combustor A gas turbine that drives a generator, a carburetor that liquefies the carbon dioxide gas separated by the carbon dioxide gas evaporator using liquefied natural gas, and gasifies the liquefied natural gas, and a liquid carbon dioxide gas in the storage tank. Is formed from a liquid level control device for controlling the level of the liquid at a constant level.

According to the present invention, the pressure of the liquid carbon dioxide gas stored in the storage tank is increased by a pump, introduced into a carbon dioxide gas evaporator, and re-vaporized using the heat energy of the gas turbine exhaust gas. The re-vaporized carbon dioxide gas is supplied to the combustor.
The combustor is supplied with city gas and oxygen, which are clean fuels, in addition to carbon dioxide as a working fluid.

The combustion gas generated in the combustor is supplied to a gas turbine as a power source for driving a generator. Gas turbine exhaust gas discharged from the gas turbine is introduced into a carbon dioxide gas evaporator, and carbon dioxide in the exhaust gas is separated.
The separated carbon dioxide gas is introduced into a vaporizer to gasify the liquefied natural gas, while liquefying itself into liquid carbon dioxide gas. On the other hand, the level of the liquid carbon dioxide in the storage tank is controlled to be constant by the liquid level controller.

Further, the present invention is provided with an oxygen booster for recirculating the remaining oxygen separated from the storage tank for storing the liquid carbon dioxide gas to the combustor, thereby reducing the amount of oxygen supplied from the oxygen supply source. can do.

Further, according to the present invention, a preheater is provided in the middle of the path from the pump to the carbon dioxide gas evaporator, and the heat medium of another system is cooled by the liquid carbon dioxide gas pressurized by the pump. The retained cold can be used more effectively.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a first example of a cryogenic power generator according to the present invention. This cold-heat power generator includes a combustor 1 that uses clean city gas as a fuel, a gas turbine 2 that drives a generator 10, a heat exchange type heater 3, a carbon dioxide separator 4, and a blower 5. , Heat exchange type vaporizer 6
And a vertical storage container 7 and a pump 8. In addition, the gas turbine 2 is provided with an expansion turbine 11 so as to contribute to the power generation of the power generator 10.

The storage container 7 stores a low-temperature liquid carbon dioxide gas a '. The liquid carbon dioxide gas a ′ is pressurized to the required pressure of the gas turbine 2 by the pump 8 and then supplied to the carbon dioxide separator 4 where it is re-vaporized by the high-temperature gas turbine exhaust gas e discharged from the gas turbine 2. You. Therefore, a conventional air compressor for increasing the pressure of combustion air is not required.

The re-vaporized high-pressure carbon dioxide gas a ″ is supplied to the combustor 1. In the combustor 1, carbon dioxide gas a ″ as a working fluid, clean city gas c as fuel, and city gas are used. Oxygen b, which is used for the combustion of, is introduced. In this case, the residual oxygen is recirculated, and eventually consumes the theoretical amount of oxygen.

High temperature and high pressure combustion gas d generated in the combustor 1
Is a gas turbine 2 as a power source for driving the generator 10.
Supplied to After engaging in power generation, the gas turbine exhaust gas e discharged from the gas turbine 2 is introduced into the carbon dioxide gas separator 4 via the heater 3. Then, the carbon dioxide gas a in the gas turbine exhaust gas e is separated by the carbon dioxide gas separator 4.

The separated carbon dioxide gas a is introduced into the LNG vaporizer 6 by the blower 5 to gasify the liquefied natural gas f. The liquid carbon dioxide gas a ′ liquefied by the liquefied natural gas f is stored in the storage container 7.

The gas turbine exhaust gas e is a gas mainly composed of carbon dioxide gas, residual oxygen and water (steam). The steam is condensed by the carbon dioxide separator 4 and can be easily separated. is there. Other than steam, it is a non-condensable gas.

Since part of the city gas c is converted into carbon dioxide by combustion, the carbon dioxide discharged from the gas turbine 2 in accordance with the supplied fuel has a low temperature even after being discharged from the carbon dioxide separator 4. Have pressure.

[0027] Therefore, if the waste gas is discharged into the atmosphere as it is, wasteful energy is consumed. Therefore, these are introduced into the expansion turbine 11 through the heater 3 located upstream of the carbon dioxide gas separator 4. Again, it is possible to contribute to power generation. Thereby, high efficiency can be achieved.

On the other hand, the turbine blades (not shown) of the gas turbine 2 are cooled by high-pressure carbon dioxide gas a ″ supplied through a branch pipe 13 branched from a pipe 12 before the combustor 1. Has become.

As described above, according to the present invention, a part of the liquefied natural gas liquefied energy can be efficiently recovered as electric power by effectively utilizing the cold heat of the liquefied natural gas. In particular, since the gas turbine exhaust gas after separating carbon dioxide from the gas turbine exhaust gas is introduced into an expansion turbine provided in the gas turbine, high efficiency can be achieved.

Further, an air compressor is not required, and the cost is lower than that of an existing gas turbine. That is, one of the factors is that the output of the turbine of the same size increases because the compressor driving power is added to the power generation output. Therefore, the construction cost can be reduced. Furthermore, because the oxygen concentration required for combustion in the combustor can be freely controlled,
The oxygen concentration in the combustion exhaust gas can be reduced, and NO
It can also contribute to the reduction of x and the like. Moreover, since carbon dioxide is used as the working fluid, it is environmentally safe.

Although this cooling / heating power generator includes the heater 3, the heater 3 is not required in principle. The liquid carbon dioxide gas a ′ pressurized by the pump 8 is re-evaporated by the turbine exhaust gas e of the gas turbine 2, but the heat medium of another system is heated to a certain temperature, for example, a saturation temperature under the pressure. After being used as cold heat for cooling, it may be introduced into the carbon dioxide gas separator 4.

The unit price required for producing oxygen to be supplied to the combustor is generally high. However, if a cryogenic separation method utilizing the cold heat of liquefied natural gas is used, the production can be performed at a relatively low cost. .

FIG. 2 shows a second embodiment of the thermal power generator according to the present invention. The cold-heat power generator includes a combustor 1 using clean city gas as fuel, a gas turbine 2 driving a generator 10, a blower 5, a heat exchange type vaporizer 6, and a vertical storage container 7. , A pump 8, a carbon gas evaporator 14, and a preheater 15.

The storage container 7 stores the low-temperature liquid carbon dioxide gas a '. This liquid carbon dioxide gas a ′ is boosted to the required pressure of the gas turbine 2 by the pump 8 and then supplied to the carbon dioxide gas evaporator 14 via the preheater 15, where the high-temperature and high-pressure gas discharged from the gas turbine 2 is discharged. It is re-vaporized by the turbine exhaust gas e. Therefore, a conventional air compressor for increasing the pressure of combustion air is not required.

The re-vaporized high-pressure carbon dioxide gas a ″ is supplied to the combustor 1. In the combustor 1, carbon dioxide gas a ″ as a working fluid, clean city gas c as fuel, and city gas are used. Oxygen b, which is used for the combustion of, is introduced. In this case, a theoretical amount of oxygen is consumed.

High temperature and high pressure combustion gas d generated in the combustor 1
Is a gas turbine 2 as a power source for driving the generator 10.
Supplied to After engaging in power generation, the gas turbine exhaust gas e discharged from the gas turbine 2 is supplied to the carbon dioxide evaporator 1
4 and the condensed water h is discharged out of the system. In the figure, reference numeral 16 indicates a valve.

The carbon dioxide gas a and the residual oxygen b not condensed in the carbon dioxide gas evaporator 14 are separated by the blower 5 into LNG.
The liquefied natural gas f is introduced into the vaporizer 6 and gasified.
Liquid carbon dioxide a ′ liquefied by liquefied natural gas f
Is stored in the storage container 7 again.

In the case of the present invention, the carbon dioxide gas is newly generated by the combustion of the city gas c, so that the amount of the carbon dioxide gas gradually increases. Therefore, the liquid level control device 1 is controlled so that the liquid carbon dioxide gas a ′ stored in the storage container 7 has a constant liquid level.
7 needs to be controlled. The liquid level control device 17
It comprises a valve 19 provided on a pipe 18 connected to the bottom of the storage container 7, a controller 20 for controlling the valve 18, and an oscillating float 21 attached to the controller 20.

The non-liquefied oxygen b is compressed by an oxygen compressor 22 as an oxygen booster, and then re-supplied to the combustor 1 through a pipe 23 and an oxygen supply pipe 24. Thereby, the amount of oxygen supplied from a supply source (not shown) can be reduced.

In the present invention, the heat medium i of another system is cooled by using the preheater 15. The reason is that the liquid carbon dioxide gas pressurized by the pump 8 is re-evaporated by the turbine exhaust gas e of the gas turbine 2, but the heat medium of another system is heated to a certain temperature, for example, a saturation temperature under the pressure. This is because it may be used as cold heat for cooling and then introduced into the carbon dioxide gas evaporator 14.

On the other hand, it is desirable that the liquid carbon dioxide gas a ′ discharged out of the system by the liquid level control device 17 be used effectively. For example, in the case of the conventional gas turbine shown in FIG. 3, since the surplus liquid carbon dioxide gas a ′ is liquid, the injection pressure for supplying to the gas turbine can be increased by the pump 38. When supplied to the combustor 31, the amount of intake air of the compressor 41 can be reduced. As a result, the compression power can be reduced, and the power generation efficiency can be improved. In the figure, the symbol n indicates intake.

In the figure, reference numeral 32 denotes a gas turbine, 3
3 is a heater, 34 is a liquid carbon dioxide vaporizer, 37 is a storage container, and 40 is a generator.

FIG. 4 shows a third example of a cryogenic power generator according to the present invention. In the present example, the oxygen b mixed in the liquid carbon dioxide a ′ is separated from the second example in which the oxygen b separated from the liquid carbon dioxide storage device 7 is re-supplied to the combustor 1 by the oxygen compressor 22. Part of the equipment (oxygen compressor) by the method of sucking and recirculating the pump 8 without releasing it
Is to be removed.

In the combustion process, most of the oxygen is consumed (converted to carbon dioxide gas), and the remaining oxygen is reduced to the limit (a range that does not impair the combustion stability of the combustor). Therefore, the problem (cavitation) at the time of suction of the pump 8 can be avoided by selecting the material of the impeller, though there is some concern.

Regarding other devices, the same parts as those of the second example are denoted by the same reference numerals, and detailed description thereof will be omitted.

FIG. 5 shows a fourth embodiment of the cryogenic power generator according to the present invention. By cooling the intake air n using the cold heat of the carbon dioxide gas a ″ as in this cold power generation device, it is possible to compensate for a reduction in the summer output of the gas turbine 32.

In the figure, reference numeral 31 denotes a combustor, 32 denotes a gas turbine, 33 denotes a heater, 34 denotes a liquid carbon dioxide vaporizer, 36 denotes an LNG vaporizer, 37 denotes a storage container, 38 denotes a pump, and 40 denotes power generation. , 41 indicates an air compressor, and 42 indicates an intake air cooler.

[0048]

EXAMPLES (Example 1) Table 1 shows various conditions and performances of the cryogenic power generator shown in FIG. It can be seen from Table 1 that an unprecedented power generation efficiency can be obtained. In addition, in the case of the present invention 1, the turbine pressure is assumed to be significantly higher than the conventional one, but the pressure ratio (72 / 6.5 ≒ 11.8)
Can be manufactured with the same number of turbine stages as before.

[0049]

[Table 1]

(Example 2) Table 2 shows various conditions and performances of the thermoelectric generator shown in FIG. From Table 2, it can be seen that an unprecedentedly high power generation efficiency can be obtained.

[0051]

[Table 2]

[0052]

As described above, according to the first aspect of the present invention, a part of the liquefied natural gas liquefied energy is efficiently recovered as electric power by effectively utilizing the cold heat of the liquefied natural gas. It is possible to In particular, since the gas turbine exhaust gas after separating carbon dioxide from the gas turbine exhaust gas is introduced into an expansion turbine provided in the gas turbine, high efficiency can be achieved.

Further, the present invention does not require an air compressor and is less expensive than existing gas turbines. Further, construction costs can be reduced. Furthermore, because the oxygen concentration required for combustion in the combustor can be freely controlled,
The residual oxygen concentration in the combustion exhaust gas can be reduced,
This can contribute to the reduction of NOx and the like. Moreover, since carbon dioxide is used as the working fluid, it is environmentally safe.

Further, the invention according to claim 2 provides a heater disposed upstream of the carbon dioxide separator immediately before introducing the remaining gas turbine exhaust gas from which the carbon dioxide has been separated by the carbon dioxide separator into the expansion turbine. And reheat, power generation efficiency is further improved.

According to the third aspect of the present invention, since a part of the carbon dioxide gas supplied to the combustor is introduced into the turbine blades of the gas turbine and cooled, it is possible to increase the temperature and pressure of the gas turbine.

The invention according to claim 4 further comprises a liquid level control device for controlling the level of the liquid carbon dioxide in the storage tank to be constant. Of the combustor,
In addition to the effects described above, it is possible to reduce the intake air amount of the compressor in the conventional gas turbine. as a result,
It is possible to reduce the compression power and thereby improve the power generation efficiency.

The fifth aspect of the present invention is provided with an oxygen booster that recirculates the remaining oxygen separated from the storage tank for storing the liquid carbon dioxide gas to the combustor. It is possible to reduce the amount of oxygen supplied from the supply source.

According to the sixth aspect of the present invention, until the temperature reaches a certain temperature, for example, a saturation temperature under a predetermined pressure, the heat is supplied to the carbon dioxide evaporator as cold heat for cooling the heat medium of another system. Liquid carbon dioxide can be used effectively.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first example of a thermal power generation device according to the present invention.

FIG. 2 is a schematic diagram showing a second example of the thermal power generation device according to the present invention.

FIG. 3 is a schematic diagram of a conventional power generation system using excess liquid carbon dioxide.

FIG. 4 is a schematic diagram showing a third example of a thermal power generator according to the present invention.

FIG. 5 is a schematic diagram of a cryogenic power generation device configured to cool intake air by using the cold heat of carbon dioxide gas.

FIG. 6 is a schematic diagram of a conventional thermal power generation device employing a Rankine cycle system.

FIG. 7 is a schematic diagram of a conventional thermal power generation device employing a natural gas direct expansion system.

FIG. 8 is a schematic diagram of a conventional thermal power generation device employing a multiple medium application method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Combustor 2 Gas turbine 4 Carbon dioxide separator 6 Vaporizer 7 Storage tank 8 Pump 11 Expansion turbine a 'Liquid carbon dioxide gas b Oxygen c Fuel d Combustion gas e Gas turbine exhaust gas f Liquefied natural gas

Claims (6)

[Claims] 1. A storage tank for storing liquid carbon dioxide gas, a pump for pumping liquid carbon dioxide gas from the storage tank to increase its pressure, and re-vaporizing the liquid carbon dioxide gas discharged from the pump using gas turbine exhaust gas. A carbon dioxide separator for separating carbon dioxide in turbine exhaust gas, a combustor for burning clean fuel in the presence of carbon dioxide re-evaporated by the carbon dioxide separator and oxygen, and a gas generated in the combustor. A gas turbine that drives a generator using combustion gas as a power source, and liquefies the carbon dioxide gas separated by the carbon dioxide separator using liquefied natural gas, and vaporizes the liquefied natural gas, An expansion turbine that is provided alongside the gas turbine and that introduces the remaining gas turbine exhaust gas from which carbon dioxide has been separated by the carbon dioxide separator. apparatus. 2. The method according to claim 1, wherein the gas turbine exhaust gas from which the carbon dioxide gas has been separated by the carbon dioxide gas separator is reheated by a heater disposed upstream of the carbon dioxide gas separator immediately before the gas turbine exhaust gas is introduced into the expansion turbine. The thermal power generator according to claim 1. 3. The thermal power generator according to claim 1, wherein a part of the carbon dioxide gas supplied to the combustor is introduced into turbine blades of the gas turbine. 4. A storage tank for storing liquid carbon dioxide gas, a pump for pumping liquid carbon dioxide gas from the storage tank to increase the pressure, and re-vaporizing the liquid carbon dioxide gas discharged from the pump using gas turbine exhaust gas. A carbon dioxide evaporator for separating carbon dioxide in turbine exhaust gas, a combustor for burning clean fuel in the presence of carbon dioxide re-evaporated by the carbon dioxide evaporator and oxygen, and a combustor generated in the combustor A gas turbine that drives a generator using combustion gas as a power source, a carburetor that liquefies carbon dioxide separated by the carbon dioxide evaporator using liquefied natural gas, and gasifies liquefied natural gas, and a storage tank. A thermoelectric generator comprising a liquid level control device for controlling the level of liquid carbon dioxide in the chamber to a constant level. 5. The cryogenic power generator according to claim 4, further comprising an oxygen booster for recirculating the remaining oxygen separated from the storage tank for storing the liquid carbon dioxide gas to the combustor. 6. The refrigeration system according to claim 4, wherein a preheater is provided in the middle of the path from the pump to the carbon dioxide gas evaporator, and the heat medium of another system is cooled by the liquid carbon dioxide gas pressurized by the pump. Power generator.